Human Auditory Cortex Physiology Speech sounds are the most important sounds that we hear;yet little is known about how these stimuli are represented within human auditory cortex. The goal of our research is to understand the functional organization and connections of those areas of human cerebral cortex that are engaged in sound processing and examine how auditory and visual speech stimuli are represented in these regions. These experiments involve direct electrophysiological recording from, and electrical stimulation of, the cerebral cortex of awake human subjects undergoing clinical evaluation of intractable epilepsy. We will pursue our goals by testing a series of specific hypotheses regarding: 1) the locations and functional properties of auditory cortical fields, 2) the manner in which evoked responses to speech stimuli are represented and transformed within these fields, 3) the influence of visual speech information and competing background noise on cortical processing within these fields, and 4) the functional connections and patterns of information flow between these fields. These objectives are pursued by an experienced multidisciplinary team using direct investigative methods in order to gather complimentary sets of human physiological and anatomical data. The resulting measurements cannot be obtained using non-invasive techniques. We pursue these objectives believing that knowledge of the fundamental structure and function of the normal human auditory system is essential to understanding mechanism that underlie impairment of all aspects of hearing, speech, and language.